From: Christoph Hellwig <hch@lst.de>
Date: Thu, 27 Aug 2015 12:17:01 +0000 (+0200)
Subject: scsi_dh: don't allow to detach device handlers at runtime
X-Git-Url: http://git.cdn.openwrt.org/?a=commitdiff_plain;h=d44227749500d8b88a1c079bc04f69187eaf8747;p=openwrt%2Fstaging%2Fblogic.git

scsi_dh: don't allow to detach device handlers at runtime

The I/O submission and completion paths call into the device handler
without any synchronization agains detachment.  So disallow detaching
device handlers at runtime.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: James Bottomley <JBottomley@Odin.com>
---

diff --git a/drivers/scsi/scsi_dh.c b/drivers/scsi/scsi_dh.c
index 2e1db5738ae1..9f6511da5023 100644
--- a/drivers/scsi/scsi_dh.c
+++ b/drivers/scsi/scsi_dh.c
@@ -181,8 +181,10 @@ store_dh_state(struct device *dev, struct device_attribute *attr,
 			/*
 			 * Detach from a device handler
 			 */
-			scsi_dh_handler_detach(sdev);
-			err = 0;
+			sdev_printk(KERN_WARNING, sdev,
+				    "can't detach handler %s.\n",
+				    sdev->handler->name);
+			err = -EINVAL;
 		} else if (!strncmp(buf, "activate", 8)) {
 			/*
 			 * Activate a device handler